Toddlers should not spend much time behind a screen. IMHO the use of media is far more relevant than the content of the media, particularly if the time is quite limited. The very most I would consider is an hour a day, and I would not let it be at one sitting.
I've searched the web, and there's lots of info on limiting TV time and video games, but I can't find any recommendations on limiting use if it's only educational games.
That should tell you something. The difference between "educational" media and regular media is marginal compared to the difference between real life and any media.
I'm not recommending that you let your toddler spend even 5 minutes a day on Grand Theft Auto, but don't rationalize multiple hours a day with the electronic baby sitter because the content is "educational."
Get the kid a puppy. Find a good playground. Find other kids his age and have play dates. Get Lincoln Logs or Knex. Read to your kidRead to your kid. Get dolls or action figures. You get the point ... you want active rather than passive amusement.